Powder classifier

Abstract

The present invention provides a powder classifier using a classification rotor capable of classifying powder with high efficiency and high accuracy. The classification rotor is attached to a rotating shaft as a body and rotatably supported in a casing. Within the classification rotor, a cavity is formed from the outer edge to the center and classifying vanes are provided around the circumference. The cavity is bent downwardly near the center with the lower end connected through a fine powder passage to a fine powder outlet. The outer edge of the classification rotor is connected to a coarse powder outlet. After feeding powder from a powder supply port, the powder is rotated by the classifying vanes such that coarse powder particles are taken out from the rough outlet by centrifugal force and fine powder particles are taken out by airflow from the fine powder outlet.

What is claimed is: 
     
       1. A powder classifier having a casing in which a classification rotor with a rotating shaft is rotatably mounted such that powder are classified by balancing centrifugal force caused by the rotation of the classification rotor and airflow in the classification rotor, characterized in that: said casing is provided with a powder supply port in the center, an air intake portion and a coarse powder outlet in the outer edge and a fine powder outlet nearby said rotating shaft, and   said classification rotor is provided with a vent cavity formed between two disks having substantially the same diameter and arranged in parallel to each other so that the air taken in from said air intake portion will be circulated in the axial direction, with a plurality of classifying vanes provided around the circumference of the vent cavity, the classifying vanes communicating with a ring-like powder intake formed on one of said disks through which the powder fed from said powder supply port is introduced into said vent cavity after being scattered on the surface of said classification rotor, said vent cavity being bent nearby said rotating shaft to communicate with said fine powder outlet.   
     
     
       2. A powder classifier according to claim 1, wherein the sectional area of said vent cavity perpendicular to the ventilating direction is gradually reduced from the outer edge to the center of said classification rotor.